1 February 2019
First thoughts on the Brumadinho tailings dam collapse video
The video that has emerged today in Brazil showing in high resolution the collapse the Brumadinho tailings dam is apparently genuine, no matter how sensational this might seem. The video is on Youtube, and is absolutely amazing:-
Let me include three stills from this video that illustrate what appears to have happened. The first shows the very start of the failure process At the crest of the dam active deformation can be seen – the dark line is a scarp forming as the mass moves downwards. The toe is probably bulging, but this is not really clear:-
The second shows the failure fully developed. The slope is going through a massive rotational failure that extends across the full width and involves the full height of the dam:-
The front of the mass is starting to break up. The third shows the transition to a high velocity flow:-
Further rotational slips are occurring on the back scarp, but the front of the flow is travelling very rapidly. To me this look to have the characteristics of a debris avalanche rather than a debris flow – the presence of so much dust suggests that this frontal portion might not be saturated. But I would be interested in other views.
The remarkable thing here is that the mass failed as a single landslide involving the full width and full height. There is now sense of a small slip destabilising the mass, or of a series of events, or of retrogression. I find this surprising.
There is also footage now of the flow downstream. That is also deeply alarming:-
I really hope that this video will bring home the need for proper tailings management, and thus worldwide change. There can be no better illustration of just how terrifying and deadly these failures can be.